The picture shows a scanning electron microscope image showing a carefully designed chalcogenide glass deposited on a transparent substrate. These figures are called by researchers as 'meta-atoms' and they determine the mid-infrared light penetration. Material refraction
According to the consulting report of Memes, MIT and other researchers in the region jointly developed a new method for capturing images using mid-infrared spectrum, which can be applied to include thermal imaging, biomedical sensing, and Various types of applications including free space communication.
Electromagnetic radiation in the mid-IR band is a particularly useful part of the spectrum: it provides imaging in the dark, tracks thermal signals, and can sensitively detect many biological and chemical signals. But the optical system of this frequency band It is difficult to manufacture, and the application of their design are very professional and noble. At present, the researchers said that has found an efficient, large-scale production method to control and detect the wave light wave.
The results have been published in the journal Nature Communications, by Tian Gu and Juejun Hu, researchers at the Massachusetts Institute of Technology, Hualiang Zhang, a researcher at the University of Massachusetts, Lowell, and colleagues from the Massachusetts Institute of Technology, China University of Electronic Science and Technology. The other 13 researchers at East China Normal University jointly wrote.
This new method uses a flat synthetic material composed of nanostructured optical elements instead of the thick curved glass lenses commonly used in conventional optical lenses. These nanostructured optical elements can provide electromagnetic response on demand and be used similar to a computer chip. The manufacturing technology. Gu said: 'This metasurface can be manufactured using standard microfabrication techniques and its manufacture can scale up.'
Gu added: 'In the visible and near-infrared, ultra-material surface optics have shown excellent performance, but in the mid-infrared, this development has been rather slow. ' When the research team started the study, they had the ability to These devices have become very thin. The question is: 'Can we still make these materials more efficient and less expensive?' Now that they have succeeded!
The new device uses a set of precisely-shaped thin-film optical elements called 'superatoms' made of chalcogenide alloys, which have a very high refractive index to produce high performance, ultra-thin The super-atom structure. These 'super-atoms' are deposited on an IR-transparent fluorine substrate and patterned to resemble letters such as I or H. At the same time, the thickness of these tiny structures is only observed light waves. A fraction of them, they can act as a lens as a whole. In addition, these 'superatoms' can provide almost arbitrary wavefront operation, which is not achievable on larger, natural materials, while the material is very thin. Therefore, only a small amount of material is required for manufacturing. Gu said: 'This is essentially different from the traditional optical system.'
Gu continues to explain: 'The process allows us to use a very simple preparation technique that deposits material on the substrate by thermal evaporation. 'The team has demonstrated this high throughput on 6-inch wafers, micromachining standard Technology, and the research team showed: 'We are studying more mass production.'
Gu added: 'These devices can transmit 80% of mid-infrared light with optical efficiency up to 75%, which is a significant improvement over existing mid-IR meta-optics.' It is also lighter and thinner than traditional infrared optical materials. Using the same method, researchers can arbitrarily create different types of optical devices by changing the array mode. The main devices include simple beam deflectors, cylindrical or spherical Lenses, as well as complex aspheric lenses. These lenses have been shown to be able to focus mid-infrared light with a theoretical sharpness maximum, also known as the diffraction limit.
Gu said that these technologies have created meta-optical devices that can manipulate light in more complex ways than conventional large-size transparent materials, and that these devices can also control polarization and other characteristics.
Mid-infrared light has a very important position in many fields. Researchers say that mid-infrared light contains the characteristic spectral bands of most molecules and can effectively penetrate the atmosphere, so it is for environmental monitoring, military and industrial applications, etc. Key factors in the detection of various substances in the field. Due to most common optical materials used in the visible or near-infrared bands, the light in the mid-infrared band is completely opaque, so the production of mid-infrared sensors is complicated and expensive. Therefore, this This new approach will bring new potential applications including consumer sensing or imaging products.
The study was jointly funded by the US Department of Defense Advanced Research Projects Agency (DARPA) Extreme Optics and Imaging Project and the National Natural Science Foundation of China.
